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From "Tsz Wo Nicholas Sze (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-7354) Support parity blocks in block management
Date Fri, 23 Jan 2015 01:04:06 GMT

    [ https://issues.apache.org/jira/browse/HDFS-7354?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14288519#comment-14288519

Tsz Wo Nicholas Sze commented on HDFS-7354:

We could view the parity block as a part of the file so that data blocks and parity blocks
belong a block group and a file have a list of block group.

> Support parity blocks in block management
> -----------------------------------------
>                 Key: HDFS-7354
>                 URL: https://issues.apache.org/jira/browse/HDFS-7354
>             Project: Hadoop HDFS
>          Issue Type: Sub-task
>            Reporter: Zhe Zhang
>            Assignee: Zhe Zhang
> In the current block management system, each block is associated with a file. "Orphan"
blocks are considered corrupt and will be removed.
> In this JIRA we extend {{Block}} with a binary flag denoting whether it is a parity block
({{isParity}}). Parity blocks are created, stored, and reported the same way as raw ones.
They have regular block IDs which are unrelated to those of the raw blocks in the same group;
their replicas (normally only 1) are stored in RBW and finalized directories on the DataNode
depending on the stage; they are also included in block reports. The only distinction of a
parity block is the lack of file affiliation. The block management system will be aware of
parity blocks and will _not_ try to remove them.

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